Filter discovery

samples/MvcSample/FiltersController.cs

@@ -0,0 +1,21 @@
+using Microsoft.AspNet.Mvc;
+using MvcSample.Models;
+
+namespace MvcSample
+{
+    // Expected order in descriptor - object -> int -> string
+    // TODO: Add a real filter here
+    [ServiceFilter(typeof(object), Order = 1)]
+    [ServiceFilter(typeof(string))]
+    public class FiltersController : Controller
+    {
+        private readonly User _user = new User() { Name = "User Name", Address = "Home Address" };
+
+        // TODO: Add a real filter here
+        [ServiceFilter(typeof(int))]
+        public IActionResult Index()
+        {
+            return View("MyView", _user);
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.Core/Filters/IFilter.cs

@@ -3,5 +3,6 @@ namespace Microsoft.AspNet.Mvc
     public interface IFilter
     {
         // Marker only interface to any IFilter gets picked up by the DefaultActionDescriptorProvider
+        int Order { get; }
     }
 }

src/Microsoft.AspNet.Mvc.Core/Filters/IServiceFilter.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace Microsoft.AspNet.Mvc
+{
+    public interface IServiceFilter : IFilter
+    {
+        Type ServiceType { get; }
+    }
+}

src/Microsoft.AspNet.Mvc.Core/Filters/ServiceFilterAttribute.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Diagnostics;
+
+namespace Microsoft.AspNet.Mvc
+{
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
+    [DebuggerDisplay("ServiceFilter: Type={ServiceType} Order={Order}")]
+    public class ServiceFilterAttribute : Attribute, IServiceFilter
+    {
+        public ServiceFilterAttribute(Type type)
+        {
+            ServiceType = type;
+        }
+
+        public Type ServiceType { get; private set; }
+
+        public int Order { get; set; }
+    }
+}

src/Microsoft.AspNet.Mvc.Core/ReflectedActionDescriptorProvider.cs

@@ -43,6 +43,8 @@ namespace Microsoft.AspNet.Mvc
 
             foreach (var cd in controllerDescriptors)
             {
+                var controllerFilters = GetOrderedFilterAttributes(cd.ControllerTypeInfo);
+
                 foreach (var methodInfo in cd.ControllerTypeInfo.DeclaredMethods)
                 {
                     var actionInfos = _conventions.GetActions(methodInfo);
@@ -54,13 +56,24 @@ namespace Microsoft.AspNet.Mvc
 
                     foreach (var actionInfo in actionInfos)
                     {
-                        yield return BuildDescriptor(cd, methodInfo, actionInfo);
+                        yield return BuildDescriptor(cd, methodInfo, actionInfo, controllerFilters);
                     }
                 }
             }
         }
 
-        private ReflectedActionDescriptor BuildDescriptor(ControllerDescriptor controllerDescriptor, MethodInfo methodInfo, ActionInfo actionInfo)
+        private IFilter[] GetOrderedFilterAttributes(MemberInfo memberInfo)
+        {
+            var attributes = memberInfo.GetCustomAttributes(inherit: true);
+            var filters = attributes.OfType<IFilter>().OrderByDescending(filter => filter.Order);
+
+            return filters.ToArray();
+        }
+
+        private ReflectedActionDescriptor BuildDescriptor(ControllerDescriptor controllerDescriptor,
+                                                          MethodInfo methodInfo,
+                                                          ActionInfo actionInfo,
+                                                          IFilter[] controllerFilters)
         {
             var ad = new ReflectedActionDescriptor
             {
@@ -85,7 +98,7 @@ namespace Microsoft.AspNet.Mvc
 
             if (actionInfo.RequireActionNameMatch)
             {
-                ad.RouteConstraints.Add(new RouteDataActionConstraint("action", actionInfo.ActionName));   
+                ad.RouteConstraints.Add(new RouteDataActionConstraint("action", actionInfo.ActionName));
             }
             else
             {
@@ -94,7 +107,41 @@ namespace Microsoft.AspNet.Mvc
 
             ad.Parameters = methodInfo.GetParameters().Select(p => _parameterDescriptorFactory.GetDescriptor(p)).ToList();
 
+            // TODO: add ordering support such that action filters are ahead of controller filters if they have the same order
+            var actionFilters = GetOrderedFilterAttributes(methodInfo);
+
+            ad.Filters = MergeSorted(actionFilters, controllerFilters);
+
             return ad;
         }
+
+        internal List<IFilter> MergeSorted(IFilter[] actionFilters, IFilter[] controllerFilters)
+        {
+            var list = new List<IFilter>();
+
+            var count = actionFilters.Length + controllerFilters.Length;
+
+            for (int i = 0, j = 0; i + j < count; )
+            {
+                if (i >= actionFilters.Length)
+                {
+                    list.Add(controllerFilters[j++]);
+                }
+                else if (j >= controllerFilters.Length)
+                {
+                    list.Add(actionFilters[i++]);
+                }
+                else if (actionFilters[i].Order >= controllerFilters[j].Order)
+                {
+                    list.Add(actionFilters[i++]);
+                }
+                else
+                {
+                    list.Add(controllerFilters[j++]);
+                }
+            }
+
+            return list;
+        }
     }
 }